Self-retaining key



n 1957 E. D. STUHLDREHER 3,323,032

SELF-RETAINING KEY 2 Sheets-Sheet 1 Filed June 17, 1964 INVENTOR. EARL D. STUHLDREHER BY 7 FIG.2

ATTORNEYS United States Patent 3,326,032 SELF-RETAINING KEY Earl D. Stuhldreher, Hartville, Ohio, assignor, by direct and mesne assignments, to Wesley C. Meinderding, Canton, Ohio Filed June 17, 1964, Ser. No. 375,791 6 Claims. (Cl. 72-463) The present invention relates to improvements in a retaining key of the type employed to secure machine elements. More particularly, it relates to a novel retaining key adapted for selectively securing removable or replaceable machine parts subjected to high stresses. Specifically, the invention relates to a retaining key having hydraulically actuated means to cause the key to selectively engage and disengage a plurality of machine parts in wedge-like fashion.

Heretofore, tapered retaining keys have commonly been forced or wedged between machine parts for the purpose of locking them together. In many applications, the keys are hammered or driven into place resulting in damage to the keys or the adjoining parts. These key installations have proven to be satisfactory in instances where the parts are seldom replaced and it is not objectionable or costly to replace the keys each time. However, many present day equipments are designed to allow frequent interchange or replacement of parts such as cutting or shaping tools and dies.

To meet these interchangeability requirements, retaining keys which are precision formed and reusable have been developed. These keys are locked in place by more sophisticated means such as attached or engaging actuation arms or links. One of the primary problems with these mechanical actuation devices is that they are normally attached or built into one of the machine parts, such as the base or frame, thereby making it difficult to remove or replace parts when a casualty occurs in the actuation mechanism. This is particularly true in equipment such as large presses or hammers where replaceable dies are locked in position by keys which are actuated by mechanism located in the massive base or anvil section. Moreover, when the parts become worn or damaged, the whole base must be replaced at substantial expense. An example of such construction is shown in my prior Patent No. 3,075,416.

Accordingly, an object of the present invention is to provide a retaining key having actuation means located entirely within the key for selectively locking machine parts forming a keyway.

Another object is to provide a retaining key and keyway where the key can be readily engaged or disengaged despite extreme loading or shock conditions.

A further object is to provide a retaining key which is selectively locked in a keyway by hydraulic means attached to and within the retaining key.

An additional object of the invention is to provide a retaining key which can be urged into locking engagement between a base block and a tool block in a press assembly by hydraulically operated pistons and subsequently disengaged by a reverse spring bias operating on the pistons, all said operating mechanism being located entirely within the key, so that all moving parts can be serviced or replaced by removing the key for local maintenance or returning it to the manufacturer, if necessary.

These and other objects of the invention and advantages thereof will become apparent from the following description taken in conjunction with the accompanying drawings.

In the drawings:

FIG. 1 is a perspective view of a retaining key in ac- 3,326,3Z Patented June 20, 1967 cordance with the present invention shown in engaging relation between a die block and a lower base block;

FIG. 2 is an enlarged plan view of the assembly shown in FIG. 1 with portions of the die block and base block broken away to show their interrelation with the retaining key;

FIG. 3 is an enlarged fragmentary section taken substantially on line 33 of FIG. 2, with some parts being shown in elevation; and,

FIG. 4 is an enlarged fragmentary section taken substantially on line 44 of FIG. 2, with some parts being shown in elevation.

A retaining key according to the invention is adapted for various uses, for example, in a keyway formed in a base block and a tool block. The base block has a dovetail groove into which a narrower dovetail shank of the tool block is inserted. The sides of the retaining key are appropriately tapered to matingly engage one side of the tool block shank and one side wall of the base block dovetail groove. Longitudinally spaced bores in the lower surface of the retaining key contain piston assemblies which are normally biased upwardly to release the key by suitable spring means. A controlled pressurized fluid is introduced to pressure chambers in the upper ends of the piston assemblies through a suitable manifold and passages to extend the pistons from the lower surface of the retaining key against the base block to force the key upwardly into locking engagement between the tool block and the base block.

The retaining key assembly, generally indicated by the numeral 10 in FIGS. 1 and 2, is shown by way of example for securement as part of a press or hammer commonly used in the metalworking art. An anvil or base block 12 is normally rigidly attached to the frame of the press or hammer (not shown) and is of suitable size, weight, and material for the particular operation. A pair of support surfaces 13 and 14 are located on either side of a dovetail groove or slot 15 which is co-extensive with one dimension of base block 12. The dovetail slot 15 has side walls 16 and 17 which are undercut at angles of about 37 and 710 respectively depending upon the type and size of equipment employed. Side walls 16, 17 may be slightly converging as viewed from front to back in FIG. 1, or left to right in FIG. 2.

A second block, normally termed a die or tool block 20, is supported by the base block 12 in removably secured relation. A pair of reinforcing surfaces 21 and 22 on the under side of tool block 20 overlie and are disposed slightly above support surfaces 13 and 14, as best seen in FIG. 4. The tool block 20 has a dovetail extension or shank 23 which extends into the dovetail slot 15 of base block 12, but is of appreciably narrower width to accommodate a key along one side. The shank 23 has tapered sides 24 and 25 which are inclined at an angle complementary to the angle of side wall 16 so that either side 24 or 25 may be brought into mating engagement with side wall 16. The tapered sides 24, 25 do not converge along their length, even though side walls 16 and 17 of base block 12 may be so constructed. The bottom surface 26 of shank 23 slidably engages the bottom of dovetail slot 15 in base block 12 providing for transmission and dissipation of force into the base block and frame members. The top surface of tool block 20 contains a shaping, cutting, or die configuration suitable for a particular operation. Additional dies having different top surface configurations, but otherwise identical, may be provided for different operations.

The tool block 20 is locked in base block 12 by the elongated retaining key, generally indicated by the numeral 30, of substantially trapezoidal cross section which fills the keyway-like space in dovetail slot 15 not occupied by the narrower dovetail shank 23. A lower surface 31 of retaining key 30 slidably engages the bottom of dovetail slot for insertion and removal of the key. The key 30 has tapered sides 32 and 33 which converge, as viewed from front to back in FIG. 1 or left to right in FIG. 2, an amount substantially equal to the convergence of side walls 16, 17 of base block 12. Side wall 32 is tapered for complementary engagement with either of the identical sides 24 and 25 of dovetail shank 23; side wall 33 is appropriately tapered in the 7-10 range to engage.

side 17 of dovetail slot 15. The upper extremity of retaining key terminates in a top surface which is substantially parallel with but recessed slightly below support surface 13, as indicated at chain line 36, when lower surface 31 is seated on the bottom of dovetail slot 15 (FIG. 4).

At each end of retaining key 30, both the sides 32. 33

and the top and bottom surfaces 35 and 31 are beveled or chamfered as at 37 to facilitate insertion of the key into the keyway and to eliminate otherwise sharp edges protruding beyond base block 12. As best seen in :FIG. 4, the lower left corner of retaining key 30 is rounded at 38 to preclude any possibility of jamming or freezing at the acute angle formed between the bottom of dovetail slot 15 and side wall 17. In the preferred form of the invention, the retaining key 30 is controlled by a hydraulic actuation means, generally indicated by the numeral 40, which is locked entirely within the key. As shown in FIGS. 2 to 4, the retaining key 30 has a series of longitudinally spaced bores 41 opening at lower surface 31 which have their axes substantially paralleling side wall 32. Each bore 41 serves as a cylinder housing a piston assembly, generally indicated by the numeral 42, which is adapted for selective vertical positioning. Seven bores 41 and piston assemblies 42 are shown in FIG..2; however, this number may be appropriately increased or decreased depending upon the length of retaining key 30 and tool block 29 and the forces applied to the entire assembly under operating conditions.

Each piston assembly 42 has an elongated cylindrical plunger or piston 43 having an enlarged flange 44 near the medial portion thereof which slidably contacts the bore 41. Just above flange 44, each piston is surrounded by a suitable sealing or packing gland 45 backed by a collar 46' which is held in place by a retaining ring 47 threaded on the end of piston 43.

The lower side of flange 44 supports one end of a coil spring 48 which surrounds the lower projecting end of piston 43. Slightly above the lower end of eachbore 41, a conventional removable snap ring 49 is seated in an annular groove 50. A stop collar 51 seated on snap ring 49 restrains the lower end of coil spring 48. The lower end of piston 43 is rounded to form an'actuation head 52 which selectively engages the bottom of dovetail slot 15. The coil spring 48 tends to bias piston 43 upwardly so that actuation head 52 is retracted within bore 41 of retaining key 30 at which time bottom surface 31 of retaining key 30 is seated on the bottom surface of trapezoidal slot 15 in base block 12.

The hydraulic actuation means has a series of conduits in retaining key 30 which supply fluid to the piston assembly 42. A fluid chamber 55 is formed in the upper end of each bore 41 above packing gland of piston 43. Short, substantially vertical passages 56 connect the fluid chambers 55 to a manifold 57 which runs longitudinally of retaining key 30. One end of manifold 57 terminates near one end of retaining key 30; the other end terminates on the opposite end face of retaining key 30 and has an enlarged counterbore 58 in the area beyond the last piston assembly 42. A threaded plug 59 is inserted in the interiorly tapped counterbore 58 to seal the second end of manifold 57.

Near one end of retaining key 30 and above the longitudinal manifold 57, a high pressure fluid intake assembly, generally indicated by the numeral 60, is provided. A shallow bore or recess 61 is located in the top surface 35 of retaining key 30. The bottom of recess 61 is bored and tapped as at 62 to receive a high pressure intake fitting 63 which is threaded on its lower end. A high pressure fluid line 64 connected to a high pressure fluid source (not shown) is attached to intake fitting 63 by a suitable collar 65. The intake fitting 63 and collar 65 are substantially housed within the recess 61 to afford protection against accidental damage. A short inlet conduit 66 connects the lower extremity of the intake fitting 63 to the manifold 57. A check valve (not shown) may be included in intake fitting 63 or high pressure line 64 to prevent an undesired reverse flow of fluid when higher pressures develop in the key manifold 57.

When the retaining key assembly is to be employed operationally, the tool block 20 is placed atop the base block 12 with the shank 23 extending into dovetail groove 15. Either side 24 or 25 of the shank 23 may be so placed to engage side wall 16 of dovetail groove 15. The retaining key 36 is slidingly inserted in the keyway formed between the other side of the shank 23 and side wall 17 of dovetail groove 15. T he retaining key 30 is properly sized to fit snugly within the keyway, and this mating engagement may be further facilitated by the longitudinal convergence of the sides of the key and the trapezoidal slot.

Pressurized fluid is then introduced through the high and manifold 57 from which it enters the fluid chambers 55 in piston assemblies 42 by way of passages 56. Thefluid pressure overcomes the spring force biasing the pistons 43 upward causing actuation heads 52 to engage the bottom of trapezoidal slot 15 and displace retaining key 30 upwardly in wedge-like relation between base block 12 and tool block 20. The retaining key 30 is moved about the distance shown between lines 35 and 36 in FIG. 4 which is sufficient to firmly lock the adjoining members to withstand shock and longitudinal forces to which the tool block 24) may be subjected during operation of the press or hammer.

When it is desired to replace or remove the tool block, the fluid pressure is reduced so that the actuation heads 52 are retracted within the bore 41. The tapered sides 32, 33 of retaining key 30 preclude jamming or binding and allow the key to return to the bottom of the keyway when the pressure is reduced. Fluid pressure reduction may be accomplished by loosening thethreaded plug 59 or by reducing pressure in the external source supplying fluid line 64.

A preferred form of the invention has been shown and described in suflicient detail to enable one skilled in the art to practice the invention. It is apparent that modifications may bemade within the contemplation of the invention and the scope of the attached claims.

What is claimed is:

1. In a retaining key assembly the combination comprising, a base :block having a dovetail slot with converging side walls, a tool block having a dovetail shank with tapered sides adapted to matingly engage a first side wall of said dovetail slots in said base block, a retaining key having longitudinally converging sides, one side of said retaining key adapted for mating engagement with a tapered side of said tool block, the second side of said retaining key adapted for mating engagement with the second side wall of said dovetail slot in said base block, and hydraulic actuation means within said retaining key causing s aid retaining key to selectively wedgingly lock said tool block within said base block.

2. In a retaining key assembly the combination comprising, a base block having a dovetail slot wtih converging side walls, a tool block having a 'dovetai'l shank with tapered sides adapted to engage a first side wall of said dovetail slot in said base block, a retaining key having longitudinally converging sides, one side of said retaining key adapted for mating engagement with a tapered side of said tool block, the second side of said retaining key adapted for mating engagement with the second side wall of said dovetail slot in said base block, a plurality of piston assemblies longitudinally spaced in said retaining key, fluid chambers at one end of each of said piston assemblies, a manifold extending longitudinally in said retaining key, passages connecting each said fluid chamber to said manifold, a high pressure fluid intake assembly connected to said key for providing a controlled supply of fluid to said manifold, and a piston in each of said piston assemblies being actuated by fluid pressure to extend out of said retaining key for selectively moving said retaining key into wedgingly locking engagement between said tool block and said base block.

3. In a retaining key assembly the combination comprising, a base block having a dovetail slot with converging side Walls, a tool block having a dovetail shank with tapered sides matingly engaging a first side wall of said dovetail slot in said base block, a retaining key having longitudinally converging sides, one side of said retaining key matingly engaging a tapered side of said tool block, the second side of said retaining key matingly engaging the second side wall of said dovetail slot in said base block, a plurality of piston assemblies longitudinally spaced in said retaining key, fluid chambers at one end of each of said piston assemblies, a manifold extending longitudinally in said retaining key, passages connecting each said fluid chamber to said manifold, a recess in the surface of said retaining key, a high pressure intake fitting in said recess, a high pressure fluid line connected to said high pressure intake fitting and providing a controlled supply of fluid, an inlet conduit connecting said high pressure intake fitting and said manifold, and a piston in each of said piston assemblies being hydraulic-ally extensible out of said retaining key for selectively moving said retaining key transversely of a tapered side of said tool block and the second side wall of said dovetail slot in said base block into locking engagement between said tool block and said base block.

4. A retaining key for a wedge-shaped keyway comprising, tapered sides for matingly engaging a wedgeshaped keyway, a lower surface for slidably engaging the bottom of a keyway during insertion into or removal from a keyway, a plurality of longitudinally spaced bores in said lower surface, a piston assembly in each of said 1ongitudinally spaced bores, a piston in each said piston assembly extensible beyond said lower surface for selectively displacing said lower surface from the bottom of a keyway, and a hydraulic fluid system in said key for extending said pistons, whereby said tapered sides are forced into the more restricted portion of said Wedgeshaped keyway for locking engagement therewith.

5. A retaining key for a wedge-shaped keyway comprising, tapered sides for matingly engaging a wedgeshaped keyway, a lower surface adapted to slidably engage the bottom of a keyway during insertion into or removal from a keyway, a plurality of longitudinally spaced bores in said lower surface, a piston in each said bore, an enlarged flange on each said piston, a packing gland on the upper side of each said enlarged flange secured by a retaining ring, spring means normally biasing each said piston upwardly into each said bore, and conduit means within said key for selectively supplying fluid to each said fluid chamber to move each said piston into contact with the bottom of a keyway and to displace said lower surface from the bottom of a keyway, whereby said tapered sides are moved transversely of said wedge-shaped keyway for locking engagement therewith.

6. A retaining key assembly comprising, a base block, a dovetail slot in said base block having converging and undercut side Walls, a tool block having a dovetail shank with tapered sides matingly engaging a first side wall of said dovetail slot in said base block, a retaining key having longitudinally converging sides, one side of said retaining key for mating engagement with a tapered side of said tool block, the second side of said retaining key for mating engagement with the second side wall of said dovetail slot in said base block, a lower surface of said retaining key slidably engaging the bottom of said dovetail slot, a plurality of longitudinally spaced bores in said lower surface, a piston in each said bore, an enlarged flange substantially in the medial portion of each said piston, a packing gland on the upper side of each said enlarged flange secured by a retaining ring, spring means normally biasing each said piston upwardly into each said bore, a fluid chamber in the upper end of each said bore, a manifold extending longitudinally in said retaining key, passages connecting each said fluid chamber to said manifold, a top surface of said retaining key, a recess in said top surface, a high pressure intake fitting in said recess, a high pressure fluid line connected to said high pressure intake fitting and providing a controlled supply of fluid, and an inlet conduit connecting said high pressure intake fitting and said manifold, each said piston being hydraulically extensible out of said retaining key for selectively moving said retaining key transversely of a tapered side of said tool block and the second side wall of said dovetail slot in said base block into locking engagement between said tool block and said base block.

References Cited UNITED STATES PATENTS 3,075,416 1/ 1963 Stuhldreher 72-46 3 3,199,859 8/1965 Heynen 269-25 FOREIGN PATENTS 1,201,364 7/ 1959 France.

894,421 4/ 1962 Great Britain. 268,014 4/ 1950 Switzerland.

CHARLES W. LANHAM, Primary Examiner.

G. P. CROSBY, Assistant Examiner. 

1. IN RETAINING KEY ASSEMBLY THE COMBINATION COMPRISING, A BASE BLOCK HAVING A DOVETAIL SLOT WITH CONVERGING SIDE WALLS, A TOOL BLOCK HAVING A DOVETAIL SHANK WITH TAPERED SIDES ADAPTED TO MATINGLY ENGAGE A FIRST SIDE WALL OF SAID DOVETAIL SLOTS IN SAID BASE BLOCK, A RETAINING KEY HAVING LONGITUDINALLY CONVERGING SIDES, ONE SIDE OF SAID RETAINING KEY ADAPTED FOR MATING ENGAGEMENT WITH A TAPERED SIDE OF SAID TOOL BLOCK, THE SECOND SIDE OF SAID RETAINING KEY ADAPTED FOR MATING ENGAGEMENT WITH THE SECOND SIDE WALL OF SAID DOVETAIL SLOT IN SAID BASE BLOCK, AND HYDRAULIC ACTUATION MEANS WITHIN SAID RETAINING KEY CAUSING SAID RETAINING KEY TO SELECTIVELY WEDGINGLY LOCK SAID TOOL BLOCK WITHIN SAID BASE BLOCK. 